The present invention relates to a locking arrangement for foldable solar generators and, more particularly, to a locking arrangement which permits a partial unfolding of at least one of the panels of a solar generator in an intermediate position and then a folding and locking in the final position.
A locking arrangement for solar generators is shown in DE-C2-32 15 434. In the past, solar generators for satellites were comprised of several panels carrying solar cells and were pivotally connected with respective adjacent panels. In the folded-up condition, the panels were disposed on one another and prevented from unfolding by special hold-down devices; the entire stack of panels rested against the satellite body. After the start of the unfolding operation by detaching the hold-down devices, the individual panels swivelled around respective axes of rotation into an altogether flat, unfolded (i.e., folded out) position. The unfolding movement could be caused by springs which, in the area of the axes of rotation, were initially prestressed and provided necessary torques. As an alternative, motor-driven cable pull mechanisms were also used, as described, for example, in Aircraft Engineering, January 1984, Pages 2 to 5, particularly in FIG. 4.
In the case of a locking arrangement of the type shown in DE-C2-32 15 434, one of two mutually adjacent panels respectively, on its side facing the common axis of rotation, had a detent lever which, at one of its ends, was pivoted at the panel and, at its other end, carried a lock or catch pin parallel to the axis. The respective other one of the two panels, on the side facing the common axis of rotation, was equipped with a guiding element which had a curved guiding contour, specifically a semicircular edge. At its end carrying the lock pin, the detent lever was acted upon by a spring force in the direction to the common axis of rotation so that the lock pin rested against the guiding contour. The guiding contour of the guiding element ended in a locking groove essentially cut in radially with respect to the axis of rotation. In the folded-up condition of such a solar generator, the lock pin, in each case, rested against the end of the guiding contour which faced away from the locking groove.
During the unfolding operation, two mutually adjacent panels respectively pivoted around the common axis of rotation, with the lock pin sliding along on the guiding contour until it finally locked into the locking groove where it was held under the effect of the spring force directed radially toward the inside. This spring force also provided that it remained in constant contact with the guiding contour during the unfolding operation. The length of the guiding contour or the sliding path of the lock pin until it locks into the locking groove was dimensioned such that, between the folded and the unfolded position, an angular distance of in each case approximately 180.degree. was covered between two adjacent panels. The locking in the unfolded flat position of the solar generator, in each case, took place by locking of the lock pin in the locking groove where it was then held by spring force.
The solar generator, in which this known locking arrangement has been used, is brought into an altogether flat or unfolded position in a single unfolding operation. However, it sometimes required that the entire solar generator not be unfolded at once but initially, for example, only the outermost panel must be swivelled by 90.degree., while all other panels remain in the folded condition. This type of a partial unfolding may be desirable, for example, during a transfer orbit as long as the satellite has not yet reached its final, for example, geostationary, orbit, prior to which completely unfolded solar generators would be a hindrance during additional position changing or flight path changing maneuvers, such as, for example, when entering the apogee. During the partially unfolded state of the solar generators, a certain portion of the energy that can be generated is therefore already available, in order to be able to drive at least some of the energy-consuming components.
After the final orbit has been reached, the solar generator panel must be unfolded completely in which case, here also, the panels are altogether finally brought into a flat or unfolded position. In this case, also the last panel which, during the partial unfolding, had already been swivelled by approximately 90.degree. must be swivelled by approximately another 90.degree.. A locking arrangement must therefore exist between this last, i.e., outermost, panel and the second-to-the-last panel which, on one hand, makes it possible that the outermost panel is brought from the folded into the partially unfolded position, i.e., the position which is swivelled by 90.degree., and can be locked there temporarily, and which, on the other hand, ensures that the further unfolding into the flat end condition can finally take place with a subsequent locking. It may, of course, also be required that not only the outermost but, for example, the two outermost panels together must be subjected to a partial unfolding. In that case, the corresponding locking arrangement must be provided between the second-to-the-last and the panel that follows it in the direction toward the interior.
It is an object of the present invention to provide a locking arrangement which permits a partial unfolding of at least one of the panels of a solar generator composed of several panels, with low expenditures with respect to equipment and a high operational reliability. Furthermore, it is another object of the present invention to provide temporary locking of the at least one panel in an intermediate position which does not constitute the final flattened out or unfolded position of the solar generator, and the further unfolding into the final position and the subsequent locking therein.
These objects have been achieved in accordance with the present invention by providing a guiding contour which has an outer section of a curve which spans a first angular area and has a larger radial distance to a common axis of rotation, as well as a connecting inner section of a curve which spans a second angular area and has a smaller radial distance to the common axis of rotation. A plate cam with a curved outer contour is axially offset with respect to the guiding element and can be rotated around the common axis of rotation in the direction from the first toward the second angular area. A holding element hinders a lock pin after leaving the outer section of the curve of the guiding contour from carrying out a further shifting on the inner section of the curve as long as it has not been brought into engagement with the driving groove of the plate cam.
Accordingly, the guiding contour of the guiding element will now consist of two sections of a curve which connect to one another. An outer section of the curve which is characterized by a larger radial distance to the common axis of rotation is to span a first angular area. A connecting inner section of the curve which is characterized by a shorter radial distance to the common axis of rotation spans a second angular area. In addition, the plate cam is provided which is axially offset with respect to the guiding element and can be rotated around the common axis of rotation, specifically mainly in the rotating direction which is oriented from the first toward the second angular area. This plate cam has a radially cut-in driving groove and, otherwise, is to be provided with a curved outer contour like the guiding element. The radial distance of the outer contour from the common axis of rotation is, however, shorter than that of the outer section of the curve and longer than that of the inner section of the curve of the guiding contour of the guiding element. Finally, the holding element prevents that after the partial unfolding has taken place, which is implemented by way of the outer section of the curve of the guiding contour, the lock pin can be shifted still further on the inner section of the curve. In this case, the holding element must be arranged such that it prevents this further shifting only as long as the lock pin is not yet in engagement with the driving groove of the rotatable plate cam. This engagement takes place at the start of the final unfolding operation which will eventually follow the partial unfolding.